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  1. #1
    RC Racer
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    Jul 2009
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    204

    Need Suggestions

    My Mini Revo started to make a loud knocking noise in it last week. People told me to look into my diffs. I will be ordering a shim set (AE21141) to see if this corrects the problem. If not, which way would you all go...
    1. Buy new diffs, bulkheads for the front and rear.
    2. Buy a new Brushed Revo ???

    I currently have a brushless VXL 380 motor, but if I spend 70 plus dollars for new diffs and bulk heads, I figure I may as well buy another car, and use the old one for parts. Since my son races a Mini Revo as well, I know that the old car will come in handy.

    2 MERV's
    2 1/18 Mini Desert Truck & Buggy

  2. #2
    RC Champion Core's Avatar
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    knocking or clicking ?

    i think i remember your thread from a week or two ago which you also described it as a "knocking" sound. the diff issue is generally described as a clicking sound, which is why i told you to check for stones stuck under the center skid.

    i'm pretty sure shimming the diffs will take care of your issue, i wouldn't start shopping around for a new truck at this point. if the problem persists maybe a video will help figure out what's wrong with it.

    also when you have your bulks apart to shim your diffs, make sure all the teeth are free of any grit and your bearings aren't binding at all. you also might want to make sure there is oil inside of your diffs too.

  3. #3
    RC Enthusiast
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    Can you hear the sound coming from a specific area of the vehicle? You might just have a small pebble stuck in one of the gears.
    Too many RC vehicles / Spektrum DX3R

  4. #4
    RC Racer
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    Jul 2009
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    Quote Originally Posted by Core
    knocking or clicking ?

    i think i remember your thread from a week or two ago which you also described it as a "knocking" sound. the diff issue is generally described as a clicking sound, which is why i told you to check for stones stuck under the center skid.

    i'm pretty sure shimming the diffs will take care of your issue, i wouldn't start shopping around for a new truck at this point. if the problem persists maybe a video will help figure out what's wrong with it.

    also when you have your bulks apart to shim your diffs, make sure all the teeth are free of any grit and your bearings aren't binding at all. you also might want to make sure there is oil inside of your diffs too.
    It is a knocking noise for sure. the teeth look good on the ring gears, spider gears, and diff. I only checked the rear diff, it still has grease in it. Tonight, I plan to look at the front diff. The thing I noticed on the froont diff, is that there was n gease on the outer part of the diff. I am wondering if it is OK to put a small amout of lithium grease in the bulk head? I am thinking that this would help the bearings lubricated. I know with my Losi Mini Desert Buggy, it comes with a small amount of Lithium grease for the diff.
    BTW.. No peebles were found. I have the car completely torn down right now. Thanks for the advice.
    2 MERV's
    2 1/18 Mini Desert Truck & Buggy

  5. #5
    RC Champion Core's Avatar
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    hm. interesting. usually it's the rear one that goes. shim it anyway because they both absolutely need to be done regardless.

    you open up the transmission to see if everything's intact there ?

    i put a little lithium grease on mine last time i tore 'em down and it only seemed to make matters worse being that the bulks aren't sealed and they accumulated grit a lot quicker than before.

  6. #6
    RC Racer
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    Jul 2009
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    Quote Originally Posted by Core
    hm. interesting. usually it's the rear one that goes. shim it anyway because they both absolutely need to be done regardless.

    you open up the transmission to see if everything's intact there ?

    i put a little lithium grease on mine last time i tore 'em down and it only seemed to make matters worse being that the bulks aren't sealed and they accumulated grit a lot quicker than before.
    Good point about the bulk heads not being sealed. I am thinking on picking up another complete diff and shims to install on the rear, first.
    I also tore the trasmission down, but did not see no signs of missing or worn teeth on the gears.
    2 MERV's
    2 1/18 Mini Desert Truck & Buggy

  7. #7
    RC Champion
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    Apr 2007
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    2,502
    did you check the spur gear? also check to make sure all of your shafts (center especially) are tight. the center ones could have come off and be spinning freely in there. since you have already taken out the diffs etc. though, i doubt you would have missed any of the things i said above..
    Good luck,
    Later

  8. #8
    RC Racer
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    I would not go buying another truck just yet. There is probably nothing wrong with your bulkheads. I would tear down the diffs, open it up, and inspect the spider gears. Buy a diff. rebuild kit if necessary, and fill with the diff lube of your choice. Be careful to tighten the three little screws evenly, and make sure the blue o-ring does not shift on you. I use a little toothpick to push it back in place if it shifts while tightening the screws. Tighten the three screws fully, but don't get ham-fisted with it.

    Use your shim kit to shim your diffs and that will probably solve your problem. Put some grease on the pinion gears inside the bulkhead, and you can put a bead of silicone or caulk on the bulkhead to seal it up if you wish.

    If it is still clicking and knocking after that, then take a video of it and post a link to it here so we can see exactly what you are talking about. Clicking is common....I've never heard of knocking before. GOOD LUCK!

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